European X-ray Calorimeter Utrecht, 25-26 October 2004

(Some) astrophysical drivers for ahigh-resolution imaging X-ray

spectrometerXavier Barcons

Instituto de Física de Cantabria (CSIC-UC)

European X-ray Calorimeter Utrecht, 25-26 October 2004

Science context

• The missing baryons: studies of the Warm and Hot Intergalactic Medium (WHIM)

• Black hole growth rate and spin evolution: measurement of the Fe line profile at different redshifts

• Accretion disk precession: binary black holes?

European X-ray Calorimeter Utrecht, 25-26 October 2004

The Warm and Hot Intergalactic Medium

European X-ray Calorimeter Utrecht, 25-26 October 2004

Main goals of WHIM studies

• Measure baryon density as a function of z (missing baryons), comparing with cold (Lyman- cloud) component.

• Chemical evolution of the Universe (groups/clusters and strong systems).

• Heating mechanisms (photoionisation, gravitational heating etc.)

• Determine cosmological distribution (filaments)

European X-ray Calorimeter Utrecht, 25-26 October 2004

The Warm & Hot IGM

• Large fraction of baryons at T~105-107 K

• IGM hotter towards low redshift (baryons falling onto potential wells)

• Extra heating might be present due to star formation & AGNs Davé et al 2002

European X-ray Calorimeter Utrecht, 25-26 October 2004

Thermal history of WHIM

Davé et al (2001)

European X-ray Calorimeter Utrecht, 25-26 October 2004

T and ion column density(Fang, Bryan & Canizares 2002)

European X-ray Calorimeter Utrecht, 25-26 October 2004

The expected column density distribution

Fang & Canizares (2000)

Expect tens of O-VIIIabsorbers per unit z with

N>1015 cm-2

European X-ray Calorimeter Utrecht, 25-26 October 2004

Doppler parameters: thermal width and turbulence

•Typical Doppler paramb~100-200 km s-1

•Larger values for stronger systems (groupsand clusters)

Fang, Byan & Canizares 2002

European X-ray Calorimeter Utrecht, 25-26 October 2004

Sensitivity: equivalent width detection limit

Rule of thumb:

For a S/N>10 spectrum, sampled to 2-3 channelsper resolution element, narrow absorption lines canbe detected with an equivalent width as small as a fraction of a channel width.

EW 0.1 eV (5 mA@ 0.5 keV) is a realistic limit for XEUS, if equipped with a

1eV-resolution spectrograph

European X-ray Calorimeter Utrecht, 25-26 October 2004

Sensitivity:expected S/N ratio

S(0.5-4.5)=10-13 cgs:10 sources/deg2

<z>~ 0.5-1.0

XEUS+STJ=2, NHI=2 1020 cm-2

Resolution ~1 eV

Exposure time ~ 100 ks

No background

European X-ray Calorimeter Utrecht, 25-26 October 2004

Sensitivity

Curve of growth for OVIII

2 eV1 eV½ eV

European X-ray Calorimeter Utrecht, 25-26 October 2004

Fe line diagnostics in distant AGN

European X-ray Calorimeter Utrecht, 25-26 October 2004

Lockman Hole800 ks XMM-Newton observation

XEUS should be able to determine redshifts and study Fe lines individually

Average rest-frame spectra show relativistic Fe-lines

type-1 AGNEW~700eV

Streblyanskaya et al., 2004

type-2 AGNEW~500eV

European X-ray Calorimeter Utrecht, 25-26 October 2004

Fe line profile in distant AGN

• A relativistic Fe line profile provides information on the innermost parts of the accretion disk and, eventually, on the SMBH itself (spin)

• Assume:– Concurrence cosmology

– L(0.5-2)=1044 erg s-1, =1.9

– Laor profile, incl=30º, Rmin=10, Rmax=400, =2.

– EW=300 eV

– 1 Ms exposure

European X-ray Calorimeter Utrecht, 25-26 October 2004

z=1 z=2

z=3 z=5 Spectralresolution

European X-ray Calorimeter Utrecht, 25-26 October 2004

Evolution of SMBH spin

• Fe line profile potentially testable out to z~3-5 for typical type 1 AGNs, but requires long exposures

• NFI’s can do better than WFI, but only one object at a time.

• Study of samples to that level of detail very unlikely

European X-ray Calorimeter Utrecht, 25-26 October 2004

Binary SMBHsand disk precession

European X-ray Calorimeter Utrecht, 25-26 October 2004

XEUS tests of binary SMBHs

• Super-massive Black Holes in galaxy centres + mergers implies binary SMBHs.

• Evidence from long-term variability in the BL Lac OJ 287 (Sillanpää et al 1988) and others.

• Binary SMBHs might be stable over very long periods (Valtaoja et al 1989)

Mergers might play animportant role in SMBH

growth along cosmic history

European X-ray Calorimeter Utrecht, 25-26 October 2004

Jet precession in 3C273

• Jet precession from VLBI long-term monioring (Abraham & Romero 1999)

Model fitsto 16 year Jet precession

European X-ray Calorimeter Utrecht, 25-26 October 2004

A binary SMBH in 3C273?

• Romero et al (1999) find that the jet precession does likely arise from precession in the accretion disk.

• Effects on the Fe line profile:– Azhimutally averaged

– Orbital period ~105 s

Incl=8º-14º

Incl=56º-62º

European X-ray Calorimeter Utrecht, 25-26 October 2004

Accretion disk precession

• Causes:– Binary SMBH, one dominating X-ray emission.

– Non-aligned SMBH spin and accretion disk axis not aligned Accretion disk precession due to the close SMBH

• The relativistic Fe emission line will change as a result of a change in inclination angle:– Shape (especially blue edge)

– Intensity

European X-ray Calorimeter Utrecht, 25-26 October 2004

Simulations

• L(2-10)= 6.25 x 1045 erg s-1, =1.6, z=0.158

• Fe line with EW=200 eV (Yaqoob & Serlemitsos 2000)

• Simulations with various inclination angles and BH angular momenta (Schwarzschild and maximally rotating Kerr

• Disk emissivity profile r-2.5

European X-ray Calorimeter Utrecht, 25-26 October 2004

XEUS/TES vs CONX/Calorimeter100 ks, inclination angles separated 4º

Sharp blue edge of Fe lineStrongly dependent on inclination

European X-ray Calorimeter Utrecht, 25-26 October 2004

Results

• XEUS/TES delivers inclination angle with precission 0.3º (90% confidence) in 100 ks.

• CONSTELLATION-X/2eV delivers inclination angle with precission 1º (90% confidence) in 100 ks.

• Spectral resolution essential• Effective area necessary to test fainter

sourcesSee Torres, Romero, Barcons & Yun (2004, ApJL, astro-ph/0308300)

European X-ray Calorimeter Utrecht, 25-26 October 2004

Do we need a CIS for this science?

• Imaging spectrometers– Point and extended

sources

– Degraded redshift sensitivity

– High efficiency

• Gratings– Point sources only

– Flat redshift sensitivity (/~constant)

– Moderate efficiency

High spectral resolution certainly needed in thefull 0.2-8 keV bandpass: 2 different instruments